Coherent control of fragmentation of methyl iodide by shaped femtosecond pulse train

Coherent control of fragmentation of CH₃I using shaped femtosecond pulse train is investigated. The dissociation processes can be modulated by changing the separation of the shaped pulse train, and the yield of I⁺ under the irradiation of the optimal pulse is significantly increased compared with that using the transform-limited pulse. We discuss the control mechanism of dissociation processes with coherent interference in time domain. A three-pulse control model is proposed to explain the counterintuitive experimental results.